Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

First images of dolphin brain circuitry hint at how they sense sound

07.07.2015

Neuroscientists have for the first time mapped the sensory and motor systems in the brains of dolophins

Neuroscientists have for the first time mapped the sensory and motor systems in the brains of dolphins. Proceedings of the Royal Society B is publishing the results, showing that at least two areas of the dolphin brain are associated with the auditory system, unlike most mammals that primarily process sound in a single area.


Probabilistic tractography in a dolphin brain was revealed used a novel technique of diffusion tensor imaging (DTI).

Image via Gregory Berns, Emory University

"Dolphins are incredibly intelligent, social animals and yet very little is known about how their brains function, so they have remained relatively mysterious," says Gregory Berns, a neuroscientist at Emory University and lead author of the study. "We now have the first picture of the entire dolphin brain and all of the white matter connections inside of it."

The researchers applied a novel technique of diffusion tensor imaging (DTI) on the preserved brains of two dolphins who died after stranding on a beach in North Carolina more than a decade ago. The method for using DTI on a non-living brain was developed relatively recently and had previously only been used for research on deceased humans, primates and rats.

The study focused on the dolphin auditory system, since dolphins - along with several other animals, such as bats - use echolocation to sense their environments. "We found that there are probably multiple areas in the dolphin brain associated with auditory information, and the neural pathways look similar to those of a bat," Berns says. "This is surprising because dolphins and bats are far apart on the evolutionary tree. They diverged tens of millions of years ago but their brains may have evolved similar mechanisms for using sound not just to hear, but to also create mental images."

"For decades, we've thought of the dolphin brain as having one primary auditory region," says co-author Lori Marino, a neuroscientist specializing in the brains of dolphins, whales and other cetaceans. "This research shows that the dolphin brain is even more complex than we realized."

Formerly on the faculty at Emory, Marino is currently the executive director of the Kimmela Center for Animal Advocacy in Utah.

Emory houses a number of preserved cetacean brains collected by Marino, via colleagues at the University of North Carolina, Wilmington, from stranding events. Various environmental agencies respond when dolphins and whales are beached, in an effort to save the animals and return them to the sea. If the animals die, parts of them may be preserved for use in scientific research.

The current study used the brains of a common dolphin and a pantropical dolphin from the Emory collection.

Previous investigations using magnetic resonance imaging (MRI) have revealed the complex anatomy of cetacean brains. But MRI scans only capture images of the brain's basic structure.

DTI focuses on the brain's white matter, or the fiber pathways that connect neurons and different regions of the brain's gray matter. DTI can detect the movement of water molecules along these fiber tracks.

The researchers used a special DTI technique for post-mortem brains developed by study co-authors Sean Foxley, Saad Jbabdi and Karla Miller at the University of Oxford.

In a living, human brain, a DTI scan takes about 20 minutes. Scanning a post-mortem brain takes much longer, however, since they contain less water. The dolphin brains posed a particular challenge since they are large - about the size of footballs - and had been preserved for years. They retained only small amounts of the water normally found in healthy tissue.

"The signal was very weak, but it was there," Berns says. "Each of the specimens required nearly 12 hours of scanning."

The data from the DTI scans allowed the researchers to map out the white matter pathways, essentially the wiring diagram for the dolphin brain, in high detail. The results show that the dolphin auditory nerve enters the brain stem region and connects both to the temporal lobe (the auditory region of many terrestrial mammals) and to another part of the brain near the apex known as the primary visual region.

The researchers hypothesize that dolphins have more than one neural area associated with sound because they are using sound for different purposes.

Dolphins emit clicks, squawks, whistles and burst-pulse sounds to communicate, navigate and hunt. Echolocation allows them to perceive objects by bouncing sound off surfaces.

"Dolphins are the most sophisticated users of biological sonar in the animal kingdom," Marino says. "They can find fish hidden from sight in sand with ease."

Experiments have shown that dolphins can echolocate on a hidden, complex 3-D shape and then pick out that shape by sight. "They can rapidly move back and forth between their senses of sight and sound," Marino says.

One dolphin's echolocation signals and echoes may be picked up by another dolphin, she adds. "They have a complex communication system and a unique ability to emit different types of sounds, like a click and a whistle, simultaneously."

The researchers hope that their map of dolphin neural circuitry will help unlock secrets of the dolphin mind, including how they communicate and perceive their environment.

"Our study was the first to use this DTI technique on a dolphin brain, and on a specimen that was more than a decade old," Berns says. "Our success opens up the possibility of using this tool to study the archived brains of all sorts of amazing animals in museum collections around the world."

Carol Clark | EurekAlert!

Further reports about: Health Sciences animals bats brain circuitry dolphins neuroscientist technique whales

More articles from Life Sciences:

nachricht Programming cells with computer-like logic
27.07.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

nachricht Identified the component that allows a lethal bacteria to spread resistance to antibiotics
27.07.2017 | Institute for Research in Biomedicine (IRB Barcelona)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

Programming cells with computer-like logic

27.07.2017 | Life Sciences

Identified the component that allows a lethal bacteria to spread resistance to antibiotics

27.07.2017 | Life Sciences

Malaria Already Endemic in the Mediterranean by the Roman Period

27.07.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>